A New Metamaterial Structure to Amplify Evanescent Waves and Its Applications in Microwave Components

Summary form only given. In this talk, we present a new structure to amplify the evanescent waves. The structure is composed of two layers. The first layer is realized by a periodic structure with unit cell of series inductor and shunt capacitor (LC), and the second layer is realized by a periodic structure with unit cell of series capacitor and shunt inductor (CL). We show that both the LC and CL structures are equivalent to the crystal bandgap metamaterials, whose equivalent permittivity and permeability have been derived. Under certain frequency bands, evanescent waves are supported in both LC and CL structures. When such two structures are cascaded together to form a bilayer, we show that evanescent waves existing in two single layers can be amplified exponentially if the resonant conditions are satisfied. Such resonant conditions are equivalent to the anti-matching conditions for the permittivity and permeability of the crystal bandgap metamaterials. We present circuit-simulation results of the LC and CL structures arid theoretical predictions of the equivalent crystal bandgap materials, which have excellent agreements. From the simulation results, we clearly observe the exponentially increasing and decreasing distribution of electric field. We further propose an experiment using lumped capacitors and inductors mounted on a printed circuit board to verify the EWA phenomena. The EWA feature in the LC-LC structure can find important applications in the new-concept microwave components, for example, the extremely-narrow band filters.